3 research outputs found
Chemical characterization of aerosol collected at Mt. Yulong in wintertime on the southeastern Tibetan Plateau
No full textIn order to evaluate the chemical composition of aerosol on the southeastern Tibetan Plateau, aerosol samples were acquired at Mt. Yulong during January to February, 2010. Eighteen elements (Al, Si, P, S, Ca, Ti, K, Cr, Mn, Fe, Ni, Zn, As, Br, Ba, Pb, Sb and Cu) and major water-soluble ions (SO42-, NO3-, Cl-, Na+, NH4+, K+, Mg2+, and Ca2+) were detected. The results show that Ca, Fe, Al, Si, S, K and Ti are major elements which mainly originate from crustal material, while SO42- and Ca2+ are the dominant anion and cation in the samples, respectively. Results of ion analysis indicate that our samples are alkaline and that the main compounds present are CaCO3, (NH4)(2)SO4, and CaSO4. The enrichment factors (EFs) determined for As, Br, Ca, Cu, S. Pb and Zn are greater than 10; in particular, EFs for As and Br are above 100. However, the high EF for As could be caused by crustal sources because the high level of As enrichment can be found commonly on the Tibetan Plateau. Analyses including Scanning Electron Microscope (SEM) observations, EF determinations, backward trajectories and correlation coefficients reveal that Al, Fe, Ca, Ti, Mn, Fe, K and Mg2+ mainly originate from crustal sources: Pb, Br, Cu, Ni, Zn and Sb come mainly from traffic-related emissions: and biomass burning influences Cl-, Br, S and P.</p
Chemical composition of rainwater at Lijiangon the Southeast Tibetan Plateau: influences from variousair mass sources
No full textDaily rainwater samples collected at Lijiang in 2009 were analyzed for pH, electrical conductivity, major ion (SO42−, Cl−, NO3−, Na+, Ca2+, Mg2+, and NH4+) concentrations, and δ18O. The rainwater was alkaline with the volume-weighted mean pH of 6.34 (range: 5.71 to 7.11). Ion concentrations and δ18O during the pre-monsoon period were higher than in the monsoon. Air mass trajectories indicated that water vapor from South Asia was polluted with biomass burning emissions during the pre-monsoon. Precipitation during the monsoon was mainly transported by flow from the Bay of Bengal, and it showed high sea salt ion concentrations. Some precipitation brought by southwest monsoon originated from Burma; it was characterized by low δ18O and low sea salt, indicating that the water vapor from the region was mainly recycled monsoon precipitation. Water vapor from South China contained large quantities of SO42−, NO3−, and NH4+. Throughout the study, Ca2+ was the main neutralizing agent. Positive matrix factorization analysis indicated that crustal dust sources contributed the following percentages of the ions Ca2+ 85 %, Mg2+ 75 %, K+ 61 %, NO3− 32 % and SO42− 21 %. Anthropogenic sources accounted for 79 %, 68 %, and 76 % of the SO42−, NO3− and NH4+, respectively; and approximately 93 %, 99 %, and 37 % of the Cl−, Na+, and K+ were from a sea salt source.</p
Long-term trends in chemical composition of precipitation at Lijiang, southeast Tibetan Plateau, southwestern China
No full text1090 precipitation samples were collected between 1989 and 2006 from the Lijiang region, an internationally important tourist site in Yunnan province, southwestern China. All the samples were analyzed for pH, electrical conductivity, SO4 2−, Cl−, NO3 −, Na+, Ca2+, Mg2+ and NH4 + concentrations. pH had a mean value of 6.08 and showed a slight increase as tourism developed between 1989 and 2006. SO4 2− and Ca2+ were the dominant anion and cation, respectively. Most of the ions showed significantly increasing trends, especially Ca2+ and Mg2+, with the exception of NH4 + that had a clearly decreasing trend. As a result, the neutralization capacity of Ca2+ increased significantly, and the precipitation NP/AP (neutralizing potential index/ acidifying potential index) ratio increased. There was a significant correlation between the soil-derived cations Ca2+ and Mg2+, and significant correlation of SO4 2− with Ca2+ and Mg2+. The sea-salt species Cl− and Na+ was not well correlated. Using Na+ as a sea-salt tracer, non-sea-salt source fractions were calculated as SO4 2−: 99.1%, Mg2+: 92.6% and Ca2+: 99.8%. Furthermore, about 95.4% of NO3 − and 41.7% of SO4 2− were contributed by anthropogenic sources, and 57.4% of SO4 2− was contributed by soil/dust sources that had a remarkably strong relationship (r=0.65, pb0.01) with the number of tourists, suggesting that human activities in a tourism-oriented city increase atmospheric dust loading.</p
